vestibular neuronitis (acoustic neuritis)

Introduction

Unilateral vestibular dysfunction without hearing loss.

Etiology

(hypotheses)

• may follow an upper respiratory tract infection in prior 2-3 weeks
• reactivation of Herpes simplex

Pathology

• vestibular dysfunction due to inflammation of the vestibular nerve (may be unilateral)

Clinical manifestations

• acute onset of severe of severe constant vertigo
  • vertigo may be exacerbated by head movements
• non-positional* peripheral vertigo
• postural imbalance, positive Rhomberg test
• dizziness
• nausea, vomiting
• no hearing loss
• no photophonophobia
• tinnitus may be noted
• ear pain or fullness in the ear may be noted
• symptoms generally last for hours, > 1-2 days
  • symptoms resolve in days to weeks
  • residual symptoms may persist for days to months to years
• head-thrust test may be positive
• Dix-Hallpike maneuver* results in delayed (~6 seconds) nystagmus with severe vertigo lasting < 1 minute

* non-positional does not preclude patient from preferring to lie in bed with eyes closed

* non-positional apparently does not apply to head-thrust test

* Dix-Hallpike maneuver does not constitute rapid positional change

Diagnostic procedures

• Weber test: midline
• Rinne test: positive (air conduction > bone conduction)

Differential diagnosis

• Meniere's disease: associated with hearing loss
• labyrinthitis: associated with hearing loss
• benign positional vertigo:
  • duration of vertigo < 24 hours
  • may be caused by head trauma
  • rotatory nystagmus provoked by rapid positional change lasts < 1 minute
  • Rhomberg test positive would be positive only during episodes of vertigo

Management

• meclizine (Antivert) 25-50 mg PO every 6 hours
• dimenhydrinate (Dramamine) 50 mg PO every 6 hours
• promethazine (Phenergan) 25-50 mg PO every 6 hours
• methylprednisolone taper over 3 weeks
  • begin 100 mg PO QD
• valacyclovir no better than placebo

More general terms

• vestibular disorder (vestibulopathy)